Offshore terminal

ABSTRACT

An offshore terminal comprising a number of axially and radially interconnected containers sunk to stand on the sea bed and extending above the sea surface, which containers have a polygon bottom which protrude from the container wall and match each other to form a continuous bottom of the terminal and closed hollows between the containers for interconnecting and ballasting purposes.

United States Patent [191 Heien [4 1 Oct. 21, 1975 OFFSHORE TERMINAL [76] Inventor: Sigurd Heien, Aslokkveien 82, 1362 Billingstad, Norway 22 Filed: July 25,1973

21 App1.No.: 382,505

[52] U.S. Cl. 61/46.5; 61/50; 52/192;

220/18 [51] Int. C l..... E02b 17/00; B65d 11/00; B65g 5/00 [58] Field of Search 61/465, 46, .5, 50;

10/1970 Chaney 61/465 1/1974 Rosenberg 114/.5 T

Primary Examiner.lac0b Shapiro Attorney, Agent, or Firm-Young & Thompson [5 7 ABSTRACT [56] References Cited and ballasting p p UNITED STATES PATENTS 8 Claims, 12 Drawing Figures 3,510,892 5/1970 Monnereau et a1. 9/8 R -;T "if US. Patent 0t.2'1, 1975 SheetlofS 3,913,335

US. Patent Oct. 21, 1975 Sheet20f5 3,913,335

US. Patent 0a. 21, 1975 Sheet 3 of5 3,913,335

US. Patent Oct. 21, 1975 I Shee t4of5 3,913,335

U.S. Patent 0a. 21; 1975' Sheets of5 H 3,913,335

OFFSHORE TERMINAL The invention relates to an offshore terminal, preferably an oil and gas storage tank and production platform, comprising a number of prefabricated, preferably cylindrical reinforced concrete containers which in floating, horizontal position are adapted to be interconnected axially to the desired length and in floating, vertical position are positioned with their axes in spaced, parallel relationship and are interconnected radially to form a desired pattern, the top of the uppermost con- 1 tainer being provided with an hollow pillar of steel with a substantially smaller cross sectional area than that of the container, and the top of the pillars support a common platform.

In the exploitation of oil or gas finds below the ocean floor, the landing of the products is often a problem. Long underwater pipe lines must, when it concerns oil, often be equipped with pumping stations, if the pipe line is to have reasonable dimensions. The pipe lines may, furthermore, be subjected to breakage and become the cause of embarrasing oil leakages. Over long distances it may therefore be more economical, and safer against oil pollution, to make use of transport by ship. If, however, such transport is to be efficient, there must, on oil fields in the open sea, be provided sufficient storage facilities and reliable loading devices for tankers.

The object of the invention is therefore to provide a terminal and tank installation of the said type, which is semimobile in that the containers are prefabricated and floated to the selected position where they are interconnected and sunk to stand on the bottom and may later be floated and towed to another position, which installation also may be used as a drilling installation.

This is according to the invention achieved in that the bottom in the lowermost container and preferably the top of the uppermost container has the form of a polygon, peferably a hexagon, which protrudes from the circumference of the container and on both sides of vertical coupling zones for interconnection by means of steel rods or cables and tensioning members which are anchored in the said bottom and top respectively, so as to keep distance between the said vertical coupling zones which protrude a short distance out of the container wall and have horizontally protruding reinforcing steel loops which overlap each other from two coupling zones to be interconnected and which take up common vertical connection members.

The common connection members may be steel tubes and the said loops and tubes are cast in concrete by means of formwork which is arranged between the lateral edges of two opposite coupling zones to be connected and the said cavities are concrete cast simultaneously.

The top of the uppermost container and the adjacent corners of containers to be interconnected are preferably cut off, so as to give access to the cavities formed by the concrete castings and the container walls between the coupling zones, for filling with ballasting material.

The dividing planes formed by the top ofa lower container and the bottom of an above adjoining container, possibly the hollow pillar, may be used for distribution of ballasting water and compressed air during sinking and raising of the terminal.

The bottom plate or base of the lowermost container about its the circumference is preferably provided with a down reaching skirt, which sinks into the sea bed and anchors the container.

The pillars may be telescopically adjustable by hydraulic means.

To diminish the danger of erosion of relatively soft sea bottom, the circumference of the terminal is provided with exterior take-up rooms which are filled with coarse material like stone before the terminal has been brought into position, which rooms have closure are releasable by means controlled from the sea surface, so that the coarse material slides out and forms more and less adjoining jetties along the foot of the terminal.

The invention is further explained in the following with reference to the drawings.

FIG. 1 is a view of a combined storage tank and production platform according to the invention.

FIG. 2 is a plan view of the combined storage tank and production platform of FIG. 1.

FIG. 3 is an enlarged plan view of the connection between two containers of FIG. 2.

FIG. 4 is a further enlarged section of the central portion of FIG. 3.

FIG. 5 is a plan view of the portion between three interconnected containers.

FIG. 6 is a sectional view along the line AA on FIG. 5, through the top plates of the containers.

FIG. 7 is a sectional view along the line AA on FIG. 5, through the bottom plates of the containers.

FIG. 8 is a plan view partly in cross section of a part of a tank unit according to a second embodiment of the invention.

FIG. 9 is a cross-sectional view along the line Il-II of FIG. 8.

FIG. 10 is a cross-sectional view along the line Ill-III of FIG. 8.

FIG. 11 is a plan view partly in cross section ofa third embodiment of a tank unit according to the invention; and Y FIG. 12 is a cross section on the line V-V of FIG. 11.

The embodiment shown in FIGS. 1-7 comprises seven containers 1 of stressed concrete prefabricated in dock and launched and interconnected radially and axially when floating. The bottom 4 and top 5 of the containers are hexagonal and project somewhat beyond the annular container wall. On the central container, and every second of the remaining six containers, a hollow pillar 2 of substantially smaller cross-sectional area than that of the containers is mounted, the said pillars supporting a common triangular platform 3. The walls of the containers are provided with vertical coupling areas 6 and on either side thereof, pairs of adjacent bottom plates and top plates respectively are interconnected by means of tensioning members 7 which are anchored in the bottom and top, respectively, and are connected by means of tensioning means 12 in recess 11 in the bottom and top, respectively. A spaced relationship being thereby formed between the coupling areas 6 in two containers to be interconnected. The coupling areas 6 are provided with a plurality of horizontally extending reinforcing loops 8 which, on pairs of containers to be interconnected, project in overlapping relationship from the coupling areas. Vertical steel tubes 9 are passed through the loops 8 and lock the loops together. Shuttering 10 is disposed on either side of the coupling areas 6, the said shuttering, with intermediate layer of packing, being secured by long screw bolts. Concrete is then cast in the shuttered cavity. The recesses 11 are also filled in after tensioning of the tensioning means 12. In the top plates, and possibly bottom plates which are connected to a top plate in an underlying container, recesses 13 are provided for filling of ballast in the form of stone or sand. Between the upper containers, pipe connections 14 for oil or gas inlet or outlet may be mounted. On the platform 3, boring platforms 15 may be mounted which project beyond the containers, and also cranes 16. The platform 3 may further be provided with a helicopter platform.

FIGS. 8-10 show part of a submerged tank unit, the single tanks 21 of which are interconnected and have along the periphery thereof a plurality of peripheral chambers 22 for receiving stones or other piece material before the tank unit is disposed in place. The chambers 22 have peripheral flaps 23 which are hinged at the bottom at 24 and kept in place at the top by a chain 25 or the like, which may release the flaps 23 by control at the surface of the sea, so that the flaps pivot outwardly around the hinges 24 toward the seabed and the stones 26 fall out over the flaps and a part of the seabed as shown in FIG. 10 and at the right side of FIG. 8.

FIGS. 11 and 12 show a third embodiment of the invention, wherein peripheral chambers 112 are formed between pairs of single tanks 111, by means of peripheral flaps 113 which are hinged at the top of the chamber at 114 and locked at the bottom at 115. The chambers 112 are, as in the first embodiment, tilled with stones or other piece material before the tank unit is disposed in place and submerged. The lock is controlled from the surface of the sea, so that the flaps 113 pivot outwardly at the top and the stones fall out on the seabed and form jetties. The hinging of the flaps at 114 may also be released under control from the surface of the sea and be provided with floating cavities, so that the flaps may float to the surface and be used for other tank units.

. Having described my invention, 1 claim:

1. An offshore terminal comprising a plurality of prefabricated cylindrical reinforced concrete containers interconnected axially and radially, hollow pillars of steel with a substantially smaller cross-sectional area than that of the containers and upstanding from the uppermost said containers, a common platform supported on the tops of said pillars, the bottoms of the lowermost containers and the tops of said uppermost containers having polygonal portions that extend radially outwardly from the cylindrical peripheries of the containers, reinforcing steel loops protruding from the tops and bottoms of the containers, the loops of laterally adjacent containers overlapping each other to provide coupling zones, and vertical connection members passing through and interconnecting the coupling zones at the tops and bottoms of the containers.

2. A terminal as claimed in claim 1, in which said loops and connection members are cast in concrete.

3. A terminal as claimed in claim 2, in which said connection members are steel tubes.

4. A terminal as claimed in claim 1, said bottoms of said lowermost containers having a downwardly extending skirt that sinks into the sea bed and anchors the terminal.

5. A terminal as claimed in claim 1, said pillars being telescopically adjustable, and hydraulic means for adjusting said pillars.

6. A terminal as claimed in claim 1, and chambers surrounding the terminal and filled with coarse material.

7. A terminal as claimed in claim 6, and means for releasing the outer walls of said chambers so that the coarse material slides out and forms adjoining jettys about the base of the terminal.

8. A terminal as claimed in claim 7, said outer walls being hingedly secured to the terminal at the base of the walls thereby to swing downwardly outwardly onto the sea bed with the coarse material on top of them. 

1. An offshore terminal comprising a plurality of prefabricated cylindrical reinforced concrete containers interconnected axially and radially, hollow pillars of steel with a substantially smaller cross-sectional area than that of the containers and upstanding from the uppermost said containers, a common platform supported on the tops of said pillars, the bottoms of the lowermost containers and the tops of said uppermost containers having polygonal portions that extend radially outwardly from the cylindrical peripheries of the containers, reinforcing steel loops protruding from the tops and bottoms of the containers, the loops of laterally adjacent containers overlapping each other to provide coupling zones, and vertical connection members passing through and interconnecting the coupling zones at the tops and bottoms of the containers.
 2. A terminal as claimed in claim 1, in which said loops and connection members are cast in concrete.
 3. A terminal as claimed in claim 2, in which said connection members are steel tubes.
 4. A terminal as claimed in claim 1, said bottoms of said lowermost containers having a downwardly extending skirt that sinks into the sea bed and anchors the terminal.
 5. A terminal as claimed in claim 1, said pillars being telescopically adjustable, and hydraulic means for adjusting said pillars.
 6. A terminal as claimed in claim 1, and chambers surrounding the terminal and filled with coarse material.
 7. A terminal as claimed in claim 6, and means for releasing the outer walls of said chambers so that the coarse material slides out and forms adjoining jettys about the base of the terminal.
 8. A terminal as claimed in claim 7, said outer walls being hingedly secured to the terminal at the base of the walls thereby to swing downwardly outwardly onto the sea bed with the coarse material on top of them. 